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Classic/Antique Car Repair/QUESTION COIL / DISTRIBUTER


Brad Hi I have two questions,  first its  in regards to a coil. Im using a test light . I have read to place one lead to the primary,  no matter which side of the coil I touch the test light goes on. Which side is consided the primary. The key side or non key side.   My second question is in regards to the distributor how much play should there be in the roter / shaft. Thanks again for your help Ken

It depends on the polarity of the cars electrical system. Most 12 volt cars are what is called negative ground. On most 12 voltsystems the neg side of the coil goes to the distributor  point. The reverse is true on positive found systems. With the key on on a negative ground system the positive side of the coil will have voltage all the time the key is on. The negative side of the coil will have voltage only when the points are closed. Did to side play should be no more than just preceptable.

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Brad Sears


All automotive including antique and collectible. However if the car has been modified I can only answer in general terms and maybe get you pointed in the right direction.


Automotive tech instructor. Syndicated auto columnist 1970's though the early 1990's. Syndicated auto radio talk show, Ask Brad About cars, CBS Radio 70's through 90's TV Show "Last Chance Garage" 1980's PBS-TV syndicated. Auto instructor for the following companies: Fram Autolyte Holly Carter AMF Ford Motor University Of Conn Blue Hills Technical School Sugar River Technical Center Grew up in a family garage in Needham Mass and turned wrenches from the age of 14.

Manchester Union Leader, Nashua Telegraph, Motor Service Magazine, Yankee Magazine, Popular Mechanics (Saturday Mechanic early 80's), Los Angeles Times, New York Times, and lots more.

More than I care to remember. Basically Franklin Technical Institute in Boston, Northeastern University, Fitchburg State Teachers College, Tufts University, and a lot of factory schools along the way.

Awards and Honors
Moto Award winner. And much more.

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